Inside the Earth: Real Cave Reference

Two kinds of cave, two kinds of space

Most caves you will want to paint or model are one of two types, and they look very different.

Limestone caves form slowly as slightly acidic water dissolves rock. Over millions of years, dripping water leaves stalactites, stalagmites, columns and thin curtains of stone. The spaces are irregular: tight passages open into large halls.

Lava tubes form much faster, while the lava is still flowing. The outside of the flow cools and hardens, and the hot lava inside drains away. They are long, round tunnels with layered basalt walls and few decorations. Over time their floors fill with mud and become flat.

If your fantasy cave mixes both without a reason, viewers may feel something is off even if they cannot say why.

Limestone halls and passages

• Jenolan Limestone Cave System: 451 photos in Australia, 338 inside and 113 of the cliffs outside, plus 3 handheld video clips of the chambers and a stalagmite close-up.
• Ancient Caves: 332 photos at Wombeyan, from huge halls to small chambers, including cracks where daylight falls in.
• Narrow Intricate Caves: 270 photos of tight passages in Queensland with cave coral, wavy floor patterns and long, thin stone curtains.

Lava tubes

AustraliaRef documented several sections of a lava tube system in Australia that runs for more than 100 kilometres. Parts have collapsed, leaving archways and open sections.

• Huge Lava Tube Arch With Collapsed Parts: 123 photos of a 25-metre-tall arch. The floor has filled with mud and bat guano over the 160,000 years since the eruption.
• Overgrowing Lava Tube: 77 photos of the start of the tube, where a large tree roots down to the floor. The cave floods in the wet season, which feeds the tree.
• Lava Wind Tunnel: 163 photos of a branching tube with a second exit, which creates a steady wind through the system.

For the volcanoes that make these tunnels, see volcano reference photos.

Where life gets in

Caves are not always dead stone. In the Cave Tree Roots pack (200 photos), roots push through the ceiling and hang in a wet, shining web. In Green Algae Covered Open Cave Domes (212 photos, Queensland), the roof has collapsed and algae has painted the stalactites green in natural light. The Coral Island Cave (235 photos) shows Palaha cave on Niue, with mineral-stained green and red limestone and rock pools that fill with sea spray. It opens straight onto a reef flat.

Frequently asked questions

How were the cave interiors lit?

It varies by pack, and that variety is useful. The Limestone Cave pack (120 photos, New Zealand) was shot on 3 visits with different lighting setups, so you can see how one place changes with the light. It also has a 1-minute tripod video of a flashlight on water, which throws rippling caustics across the cave walls. Some show caves have their own built-in lighting, and the open caves use daylight. For more on light, see lighting reference for artists.

Are cave photos as sharp as outdoor photos?

Most cave packs here are 6000 × 4000. Caves are dark and wet, though, so a few packs include some slightly soft frames where a tripod could not be used. Product descriptions say so when that is the case.

I build fantasy tabletop terrain. Which caves help?

The lava tubes are ideal for simple, modular tunnel sections. The limestone packs are better for detailed set pieces with stalactites and pools. See our fantasy terrain reference page for more ideas.